Assuming we all think oil prices are eventually going to rise, why don't investors buy it up at current prices and hold it for a couple of years?
Even if it only goes up to $40-$50 two years from now, it still gives a far better return than shares or bonds.
They do what you are saying already.
It even creates a market phenomenon known as contango where future prices are more expensive. This makes it hard to buy oil for the future to invest. Hence why most people just buy a big oil company and go long (hold the stock until oil is high and it reflects in the stock earnings/price).
>Assuming we all think oil prices are eventually going to rise
If you assume this, you assume that developed Western economies will begin consuming again or that a couple of the major oil and gas producing regions will stop doing so. I doubt the first will happen and the second is unthinkable.